Sexual selection and diversification: a multilevel analysis of mate choice cues in the bluethroat

Determining the causes and consequences of reproductive decisions is central to the understanding of evolutionary processes such as sexual selection and speciation. This research project represents an ambitious plan towards achieving a comprehensive under standing of the factors influencing the reproductive decisions faced by females when searching for appropriate mates. Using the bluethroat (Luscinia svecica) as a study model, the project investigates cues used by females in mate choice under three fundam entally different choice situations. The bluethroat is a socially monogamous bird with an extensive extra-pair mating system. It consists of several phenotypically distinct subspecies, some of which are in reproductive contact resulting in occasional hybr idization. The first part of this project deals with mate choice in situations of potential hybridisation between two subspecies, the chestnut-spotted svecica and the white-spotted cyanecula. By manipulating male spot colour to resemble males from the opp osite subspecies, we will test whether females discriminate against males on the basis of the colour of their throat spot. The second part investigates the choice of social mate within a svecica population. Through manipulation of the blue throat feathers of males, it seeks to unravel whether females base their choice on male phenotypic appearance or the quality of the territory, and how male heterozygosity feeds into this equation. The final part of the research plan concerns the choice of extra-pair mat es as sires for the offspring. Previous studies have shown that females are fertilized by genetically compatible extra-pair males. We will perform sperm motility experiments to test whether genetically dissimilar sperm are favoured by cryptic female choic e. With its combination of experiments and advanced molecular methods, this research project will make important contributions to research areas that are currently of great interest in evolutionary biology